Field of Invention
The present invention relates to a lateral gate electrode TFT (Thin Film Transistor) switch and a liquid crystal display device, and more particularly to, a TFT switch used for raising a charging capacity thereof, downsizing a volume thereof and raising the aperture ratio thereof.
Description of Prior Art
With the development of liquid crystal display technology, the PPI (pixel per inch) of panels is progressively increased. Sequentially to increase the aperture ratio, the TFT switches is downsized less and less in the manufacture so that the charging capacity of pixel electrodes needs to be increased with following. There are a few methods to raise the charging capacity of the pixel electrodes: 1. Manufacturing large sized TFTs and choosing a larger W/L (width/length) ratio, especially in products of the automobile and the industrial control will adopt these method, however, the aperture ratio is sacrificed thereof; 2. Selecting a higher mobility technology by using semiconductor technology, such as LTPS (Low Temperature Poly Silicon), IGZO (Indium Gallium Zinc Oxide); the charging capacity is raised, however, the manufacturing process is complicated and the manufacturing defect-rate is increased.
FIG. 1 shows a detailed structural diagram of the TFT 10 of the conventional technology. Sequentially, from bottom to top, are a gate electrode 16, a gate insulation layer 15 and an a-Si layer 14. The active layer 14 is disposed with two ohm-contact layers (n+) 13 where a source electrode 11 and a drain electrode 12 are individually disposed. In the conventional structure, it is impossible to raise the charging capacity and raise the aperture ratio, simultaneously.
Hence, it is necessary to provide a lateral gate electrode TFT switch and a manufacturing method using the same to solve the problem of the conventional technology.